Robert Wright, author of such thoughtful books as A Moral Animal and The Evolution of God, has an op-ed piece in the Sunday New York Times entitled, “A Grand Bargain over Evolution“. Without considering the merits of his contentious argument that moral laws exist in the some absolute sense and that we humans discover them as we go along (much like we have discovered the laws of thermodynamics), there was one part of his essay which caught my eye.
“There are plenty of evolutionary biologists who believe that evolution, given long enough, was likely to create a smart, articulate species — not our species, complete with five fingers, armpits and all the rest — but some social species with roughly our level of intelligence and linguistic complexity.
And what about the chances of a species with a moral sense? Well, a moral sense seems to emerge when you take a smart, articulate species and throw in reciprocal altruism. And evolution has proved creative enough to harness the logic of reciprocal altruism again and again.
Vampire bats share blood with one another, and dolphins swap favors, and so do monkeys. Is it all that unlikely that, even if humans had been wiped out a few million years ago, eventually a species with reciprocal altruism would reach an intellectual and linguistic level at which reciprocal altruism fostered moral intuitions and moral discourse?
There’s already a good candidate for this role — the chimpanzee.
Chimps, some primatologists believe, have the rudiments of a sense of justice. They sometimes seem to display moral indignation, “complaining” to other chimps that an ally has failed to fulfill the terms of a reciprocally altruistic relationship. Even now, if chimps are gradually evolving toward greater intelligence, their evolutionary trajectory may be slowly converging on the same moral intuitions that human evolution long ago converged on.”
Yes, chimps have a rudimentary sense of justice, including some version of reciprocal altruism. But in a 2007 paper in Science, Jensen et al. showed that there are moral decisions that humans make that seem to be absent in chimpanzees. The findings have implications both for our understanding of what makes humans unique, as well as for economic decision making.
The experiment is a variant of the ultimatum game, and demonstrates a form of altruism called altruistic punishment. Each of the players in this game get to make one decision. Player 1 is offered $100, and has to decide how much of this windfall will be shared with Player 2. As you consider this decision, you are aware that Player 2 is aware of exactly how much money you received. Once you make your offer (all, some, or none) to Player 2, they get to decide if they view it as fair. If the conclusion is yes, both of you get to keep your winnings; if they view it as unfair, both of you forfeit the money.
The game has been played many times with humans, and regularly works out like this. If Player 1 offers $50 to Player 2, everyone is happy and Player 2 accepts the deal. If the offer is only $40, Player 2 may not be happy but will accept it. But at some point (usually around $20), humans consider low-ball offers so unfair that they will reject it, even if it means that they get nothing. The idea is that this reaction punishes Player 1 for their chintzy behavior, but it comes at a cost to Player 2; after all, isn’t $20 better than nothing? Apparently, the trade-off that our brains make is between money and moral outrage, and at 20%, moral outrage wins out. Because Player 2 is giving something up to achieve this outcome, this phenomenon is called altruistic punishment, and is evident in humans from diverse cultures, suggesting that this form of ethical behavior arose sometime before we spread out and (over)inhabited the entire planet. Moreover, it is considered to be one of the ways in which we enforce social cohesiveness in human interaction. [For those of you wondering how altruistic punishment might work in real life, imagine a scenario where you are walking down the street and see a small person getting beaten by a big bully. Classical altruism theory suggests that you would not intervene unless the little guy is related to you – essentially, a variant of the selfish gene hypothesis. But that is not what humans do – they do intervene, not always but often and even at risk of personal injury, particularly when they perceive the fight as unfair. This is altruistic punishment in action.]
It turns out that chimpanzees do not exhibit altruistic punishment when playing the ultimatum game. At least under the conditions that Jensen et al. utilized, chimps readily accepted 20% of the pot (which consisted of raisins instead of dollars). There are important constraints that are worthy of further exploration (see for example Neiworth et al, 2009), but the interesting point is this: social evolution has conferred on humans more complex moral intuitions than are seen in non-human primates. It is not known at what point in our cultural evolution altruistic punishment arose, but it seems to me entirely plausible that it is a product of the specific social conditions under which humans have lived for some time. In the midst of all the handwringing over the (sadly, many) ways in which humans mistreat each other, it is heartening to know that our magnificent brains have developed ways in which to make life with our fellow man more reasonable. It appears as if there is hope for humanity after all.